In a synchronous cellular system, all base stations can achieve frame synchronization by using common time information of an external system. However, a cellular system that has been currently developed by the 3GPP is an asynchronous system where all the base stations operate based on an independent time frame. Such an asynchronous cellular system requires a complex cell search process unlike the synchronous cellular system.
Thus, a method for frame synchronization acquisition and cell search by using an additional preamble has been proposed, but this method cannot be applied to a system where no preamble exists. Another method for frame synchronization acquisition and cell search by using pilot symbols located at the beginning and the end of a sub-frame has been proposed, but this method uses too many pilot symbols.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.